1. Field of the Invention
This invention relates to an improved hot gas flue or chimney structure in a nonrecovery coke oven wall constructed of refractory bricks with alternate courses of the portion of the wall surrounding the flue openings each being defined by bricks of two different shapes to provide improve strength and gastight integrity.
2. Description of the Prior Art
Modern nonrecovery coke ovens are constructed in batteries consisting of a plurality of individual ovens arranged in side-by-side relation with adjacent ovens having common sidewalls. The battery is heated by a system of sole flues extending beneath the floor of each oven. Gases evolved during the coking process are led from the oven crown, i.e., the space above the coal charge in the oven, to the sole flues through a system of flues or chimneys, called downcomers, in the sidewalls to the sole flues for combustion to heat the charge. Hot exhaust gases are drawn from the sole flues by draft applied from a stack through a second system of flues or chimneys, called uptakes, extending up through the sidewalls. Normally the uptakes for a plurality of ovens in the battery will be connected to a common stack through a connection main conduit or duct as illustrated, for example, U.S. Pat. No. 5,114,542. During operation of such ovens, sometimes referred to as Thompson ovens, the sidewalls including the downcomers and uptakes are subjected to substantial stress due both to the high loads applied during pushing and charging and to the high temperatures and thermal shocks encountered.
In a typical commercial Thompson coke oven battery, the temperature in the oven chamber and downcomers may be in the range of 2,000.degree. to 2,400.degree. F. during the coking operation, while the temperature in the uptakes may be as high as 2,600.degree. F. during at least a portion of the cycle. At the end of the cycle the oven doors are opened and the charge of incandescent coke is pushed from the oven chamber, and a fresh charge of coal at ambient temperature is immediately deposited into the chamber. While the coal charge will ignite upon contact with the hot structure of the oven, substantial heat is immediately absorbed from the oven refractory by the coal charge, thereby subjecting the oven structure, including the sidewalls, to substantial stress due to the thermal shock. Pushing coke from an oven also places very high stresses on the sidewall as a result of pressure applied by the pushing machine to the end of the coke charge. Such stress can result in cracks in the sidewalls and these cracks frequently appear at the downcomers or uptakes where the walls are structurally weakened.
Since the entire oven system operates under a subatmosphere pressure as a result of the draft applied by the stack, any cracks in the oven sidewalls leading to the downcomers and uptakes will inherently result in gas leaking or flowing through the cracks to further erode and weaken the structure. Cracks leading to the uptakes or downcomers at a location below or near the surface of the charge can also cause excessive burning of the charge in that area thereby not only reducing the efficiency of the operation but also producing hot spots further eroding and weakening the structure at the crack.
A more serious problem may result from a crack leading into an uptake since unburned and partially burned distillation products bypass or shortcircuit the sole flues. Depending upon the extent of the leak, this can affect the temperature in the sole flues and thereby the coking rate in the oven. In any event, unburned distillation products shortcircuiting the system and leaking into the waste gas collection main may result in substantial atmospheric pollution even though the temperature in the collection main and stacks may be in the range of 1,800.degree. F. The escape of unburned hydrocarbons and particulate material as a result of such a shortcircuit can result in having to shut down the battery to repair the oven wall. It is, therefore, a primary object of the present invention to provide a coke oven wall having gas flues therein and which is of improved strength and gastight integrity.
Another object of the invention is to provide a coke oven sidewall having downcomers and uptake flues therein defined by improved refractory brick which will provide increased strength and gastight integrity for the wall.
Another object is to provide such a structure in which the sidewall is constructed of refractory brick in which alternate courses of the brick in the portion of the wall defining the downcomer and uptake flues are of two different brick shapes to provide increased strength at the corners of the flues and at the brick joints.